Surgical instrument having a plastic surface

ABSTRACT

A surgical instrument including a handle portion, a body portion, a movable handle, a tool assembly, a drive beam and a closure apparatus is disclosed. At least one of the closure apparatus and a contact surface of the tool assembly include a plastic surface. The body portion extends distally from the handle portion. The movable handle is located on the handle portion and is in mechanical cooperation with a drive member. The tool assembly includes an anvil, a cartridge assembly and a contact surface. The drive beam includes a proximal engagement portion and is configured to engage a portion of the drive member. The closure apparatus is configured to engage the contact surface of the tool assembly. At least a partial actuation of the movable handle moves the closure apparatus distally into engagement with the contact surface to approximate the anvil and the cartridge assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 11/544,982filed Oct. 6, 2006, now U.S. Pat. No. 7,845,535, and the disclosures ofeach of the above-identified applications are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a surgical instrument and disposableloading unit including a plastic surface thereon. More particularly, thepresent disclosure relates to a surgical instrument which includes aplastic surface on at least one of a closure apparatus and a contactsurface of a tool assembly.

BACKGROUND

Surgical devices wherein tissue is first grasped or clamped betweenopposing jaw structure and then joined by surgical fasteners are wellknown in the art. In some instruments, a knife is provided to cut thetissue which has been joined by the fasteners. The fasteners aretypically in the form of surgical staples but two part polymericfasteners can also be utilized.

Instruments for this purpose may include two elongated members which arerespectively used to capture or clamp tissue. Typically, one of themembers carries a staple cartridge that houses a plurality of staplesarranged in at least two lateral rows while the other member has ananvil that defines a surface for forming the staple legs as the staplesare driven from the staple cartridge. In some instruments, the closureof the two elongated members, or tool assembly, is affected by actuationof a movable handle which moves a drive beam having a closure apparatusthereon into a contact surface of a tool assembly, thus approximatingthe members of the tool assembly. A large frictional force may bepresent between the closure apparatus and the contact surface of thetool assembly, thus possibly requiring a relatively large amount offorce to be applied to the movable handle.

SUMMARY

The present disclosure relates to a surgical instrument including ahandle portion, a body portion, a movable handle, a tool assembly, adrive beam and a closure apparatus, where at least one of the closureapparatus and a contact surface of the tool assembly include a plasticsurface. The body portion extends distally from the handle portion anddefines a first longitudinal axis. The movable handle is located on thehandle portion and is in mechanical cooperation with a drive member. Thetool assembly is supported adjacent a distal end of the body portion andincludes an anvil, a cartridge assembly and a contact surface. The drivebeam includes a proximal engagement portion located adjacent a proximalend thereof and is configured to engage a portion of the drive member.The closure apparatus is located adjacent a distal end of the drive beamand is configured to engage the contact surface of the tool assembly andincludes a cutting surface in a disclosed embodiment. At least a partialactuation of the movable handle moves the closure apparatus distallyinto engagement with the contact surface to approximate the anvil andthe cartridge assembly.

In an embodiment, the closure apparatus includes at least one plasticcap at least partially covering a portion of the closure apparatus,e.g., a horizontal surface. It is disclosed that at least a portion ofthe closure apparatus is made of plastic or overmolded with plastic.

In a disclosed embodiment, the drive beam includes a plurality oflayers. It is also disclosed that the closure apparatus has an I-shapedcross section.

In an embodiment, the tool assembly defines a second longitudinal axisand is movable from a first position where the second longitudinal axisis substantially aligned with the first longitudinal axis to a secondposition in which the second longitudinal axis is disposed at an angleto the first longitudinal axis. In this embodiment, the tool assembly isable to be articulated.

In an embodiment, the closure apparatus is part of a disposable loadingunit. The present disclosure also relates to a disposable loading unitthat includes features of the closure apparatus and the tool assembly,as described above

DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical instrument aredisclosed herein with reference to the drawings, wherein:

FIG. 1 is a side perspective view from the distal end of one embodimentof the presently disclosed surgical instrument with articulating toolassembly;

FIG. 1A is a side perspective view from the proximal end of a disposableloading unit (DLU) of the surgical instrument shown in FIG. 1 includingthe tool assembly;

FIG. 2 is a side perspective view of the distal end of mounting assemblyand tool assembly, with parts separated, of the DLU of the surgicalinstrument shown in FIG. 1;

FIG. 3 is a side perspective view of the mounting assembly and theproximal body portion of the DLU shown in FIG. 1A with parts separated;

FIG. 3A is a side perspective view of a coupling member of the surgicalinstrument shown in FIG. 1;

FIG. 3B is a side perspective view of an upper mounting portion of themounting assembly of the DLU of the surgical instrument shown in FIG. 1;

FIG. 3C is a side perspective view of a lower mounting portion of themounting assembly of the DLU of the surgical instrument shown in FIG. 1;

FIG. 3D is a side perspective view from above the proximal body portion,the mounting assembly and the tool assembly of the DLU of the surgicalinstrument with the tool assembly in its non-articulated position;

FIG. 3E is a side perspective view from above the proximal body portion,the mounting assembly and the tool assembly shown in FIG. 3D with thetool assembly in an articulated position;

FIG. 3F is a side perspective view from below the proximal body portion,the mounting assembly and the tool assembly of the DLU of the surgicalinstrument with the tool assembly in its non-articulated position;

FIG. 3G is a side perspective view from below the proximal body portion,the mounting assembly and the tool assembly shown in FIG. 3F with thetool assembly in an articulated position;

FIG. 4 is a side cross-sectional view of the tool assembly of the DLUshown in FIG. 1A;

FIG. 5 is a top perspective view of the lock member actuator of theproximal body portion locking mechanism shown in FIG. 3;

FIG. 6 is a bottom perspective view of a locking member of the lockingmechanism shown in FIG. 3;

FIG. 7 is a top view of the proximal end of the DLU proximal bodyportion shown in FIG. 1A with the locking mechanism in its lockedposition;

FIG. 8 is a cross-sectional view taken along section lines 8-8 of FIG.7;

FIG. 9 is a top view of the proximal end of the DLU proximal bodyportion shown in FIG. 1A with the locking mechanism in its unlockedposition;

FIG. 10 is a cross-sectional view taken along section lines 10-10 ofFIG. 9;

FIG. 11 is a side perspective view of the DLU and surgical instrumentshown in FIG. 1 prior to attachment of the DLU to the surgicalinstrument;

FIG. 12 is a top view of the proximal end of the DLU and the distal endof the surgical instrument shown in FIG. 11 prior to attachment to thedistal end of the surgical instrument;

FIG. 13 is a top view of the proximal end of the DLU shown in FIG. 11 asthe DLU is advanced linearly into the distal end of the surgicalinstrument;

FIG. 14 is a top view of the proximal end of the DLU and the distal endof the surgical instrument shown in FIG. 12 after the DLU has beenadvanced linearly but prior to locking the DLU to the surgicalinstrument;

FIG. 15 is a top view of the proximal end of the DLU and the distal endof the surgical instrument shown in FIG. 13 after the DLU has beenadvanced linearly and rotatably locked onto the surgical instrument;

FIG. 16 is a perspective view of a locking assembly for use with asurgical instrument in accordance with an embodiment of the presentdisclosure;

FIG. 17 is a perspective view of various components of the lockingassembly of FIG. 16;

FIG. 18 is an enlarged perspective view of a portion of the lockingassembly of FIGS. 16 and 17 illustrated with the articulating toolassembly in a non-articulated position;

FIG. 19 is an enlarged perspective view of a portion of the lockingassembly of FIGS. 16-18 and including a link;

FIG. 20 is an enlarged perspective view of a portion of the lockingassembly of FIGS. 16-19 illustrated with the articulating tool assemblyin an articulated position;

FIG. 21 is an enlarged perspective view of another locking assembly foruse with a surgical instrument in accordance with an embodiment of thepresent disclosure;

FIG. 22 is an enlarged bottom perspective view of the locking assemblyof FIG. 21;

FIG. 23 is a perspective view of a drive beam having a plurality oflayers and a closure apparatus in accordance with an embodiment of thepresent disclosure;

FIG. 24 is a perspective view of the drive beam and closure apparatus ofFIG. 23 with parts separated;

FIG. 25 is a cross-sectional view of a portion of the drive beam andclosure apparatus of FIGS. 23 and 24;

FIG. 26 is a cross-sectional view of a drive beam and a closureapparatus in accordance with an embodiment of the present disclosure;

FIG. 27 is a cross-sectional view of the drive beam and closureapparatus of FIG. 26;

FIG. 28 is a perspective view of a tool assembly in accordance with anembodiment of the present disclosure; and

FIG. 29 is an assembly view of the tool assembly of FIG. 28.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed surgical instrument and DLU willnow be described in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views.

Referring to FIG. 1, surgical instrument 500 includes a handle portion510, a body portion 512, and a disposable loading unit (“DLU”) 16.Handle portion 510 includes a stationary handle 514 and a movable handleor trigger 516. Movable handle 516 is movable in relation to stationaryhandle 514 to advance a control rod 520 which projects from the distalend of body portion 512. Handle portion 510 and body portion 512 may beconstructed in the manner disclosed in U.S. Pat. No. 6,330,965 which ishereby incorporated herein in its entirety by reference. Alternately,other surgical instruments can be used with DLU 16 to perform endoscopicsurgical procedures.

Referring to FIGS. 1 and 1A, briefly, DLU 16 includes a tool assembly17, a proximal body portion 200 and a mounting assembly 202. Bodyportion 200 has a proximal end adapted to releasably engage the distalend of a surgical instrument 500 (FIG. 11) in the manner to be discussedin detail below. Mounting assembly 202 is pivotally secured to a distalend of body portion 200 and is fixedly secured to a proximal end of toolassembly 17. Pivotal movement of mounting assembly 202 about an axisperpendicular to a longitudinal axis of body portion 200 affectsarticulation of tool assembly 17 between a non-articulated position inwhich the longitudinal axis of tool assembly 17 is aligned with thelongitudinal axis of body portion 200 and an articulated position inwhich the longitudinal axis of tool assembly 17 is disposed at an angleto the longitudinal axis of body portion 200.

Referring to FIGS. 2-4, tool assembly 17 includes a cartridge assembly18 and an anvil assembly 20. Anvil assembly 20 includes an anvil portion28 having a plurality of staple deforming concavities 30 (FIG. 4) and acover plate 32 secured to a top surface of anvil portion 28. Cover plate32 and anvil portion 28 define a cavity 34 (FIG. 4) therebetween whichis dimensioned to receive a distal end of a drive assembly 212 (FIG. 3).Cover plate 32 encloses the distal end of drive assembly 212 to preventpinching of tissue during actuation of DLU 16. A longitudinal slot 38extends through anvil portion 28 to facilitate passage of a retentionflange 40 of drive assembly 212. A camming surface 42 formed on anvilportion 28 is positioned to engage a pair of cam members 40 a supportedon retention flange 40 of drive assembly 212 to effect approximation ofthe anvil and cartridge assemblies. A pair of pivot members 44 areformed. A pair of stabilizing members 50 engage a respective shoulder 52formed on carrier 48 to prevent anvil portion 28 from sliding axially inrelation to staple cartridge 54 as camming surface 42 is pivoted aboutpivot members 44.

Cartridge assembly 18 includes carrier 48 which defines an elongatedsupport channel 56 which is dimensioned and configured to receive staplecartridge 54. Corresponding tabs 58 and slots 60 formed along staplecartridge 54 and elongated support channel 56, respectively, function toretain staple cartridge 54 at a fixed location within support channel56. A pair of support struts 62 formed on staple cartridge 54 arepositioned to rest on side walls of carrier 48 to further stabilizestaple cartridge 54 within support channel 56. Carrier 48 has slots 46for receiving pivot members 44 of anvil portion 28 and allowing anvilportion 28 to move between spaced and approximated positions.

Staple cartridge 54 includes retention slots 64 (FIG. 2) for receiving aplurality of staples or fasteners 66 and pushers 68. A plurality oflaterally spaced apart longitudinal slots 70 extend through staplecartridge 54 to accommodate upstanding cam wedges 72 of an actuationsled 74 (FIG. 2). A central longitudinal slot 76 extends alongsubstantially the length of staple cartridge 54 to facilitate passage ofa knife blade 78 (FIG. 4). During operation of surgical stapler 10,drive assembly 212 abuts actuation sled 74 and pushes actuation sled 74through longitudinal slots 70 of staple cartridge 54 to advance camwedges 72 into sequential contact with pushers 68. Pushers 68 translatevertically along cam wedges 72 within fastener retention slots 64 andurge fasteners 66 from retention slots 64 into staple deforming cavities30 (FIG. 4) of anvil assembly 20.

Referring to FIG. 3, mounting assembly 235 includes an upper mountingportion 236 and a lower mounting portion 238. A centrally located pivotmember 284 extends from upper mounting portion 236 through a respectiveopening 246 a formed in a first coupling member 246. Lower mountingportion 238 includes a bore 239 for receiving pivot member 284 (see FIG.3F). Pivot member 284 extends through bore 239 and opening 247 a of asecond coupling member 247. Each of coupling members 246, 247 includesan interlocking proximal portion 246 b, 247 b configured to be receivedin grooves 290 formed in the distal end of an inner housing which isformed from upper and lower housing halves 250 and 252. Coupling members246, 247 retain mounting assembly 235 and upper and lower housing halves250 and 252 in a longitudinally fixed position in relation to each otherwhile permitting pivotal movement of mounting assembly 235 in relationthereto.

Referring to FIGS. 3A-3C, each coupling member 246, 247 includes acantilevered spring arm 246 c which has a distal end 246 d positioned toengage mounting assembly 235. More specifically, upper mounting portion236 includes a top surface 236 a which includes a recess 236 bdimensioned to receive distal end 246 d of spring arm 246 c of arespective coupling member 246. Lower mounting portion 238 includes abottom surface 238 a having a pair of raised surfaces 238 b which definea recess 238 c which is dimensioned to receive spring arm 247 c of arespective coupling member 247. Alternatively, at least one recess maybe formed in the proximal end of tool assembly 17.

As illustrated in FIGS. 3D-3G, when distal end of spring arms 246 c, 247c of coupling members 246, 247 are positioned in recesses 236 b and 238c of upper and lower mounting portions 236 and 238, respectively, springaims 246 c, 247 c retain mounting assembly 235 in a non-articulatedposition. Spring arms 246 c, 247 c will retain mounting assembly 235 inits non-articulated position until a predetermined force sufficient todeflect spring arms 246 c from recesses 236 b and 238 c is applied toeffect articulation of mounting assembly 235 and tool assembly 17. Whenthe predetermined force is applied to the mounting assembly 235 and toolassembly 17, spring arms 246 c, 247 c will spring or deflect outwardlyfrom recesses 236 b and 238 c, as shown in FIGS. 3E and 3G, to permitpivotal movement of mounting assembly 235 (and, thus, tool assembly 17)in relation to the distal end of proximal body portion 200 of the DLU16.

As discussed above, spring arms 246 c and recesses 236 b and 238 cmaintain tool assembly 17 in its non-articulated position until apredetermined force has been applied to mounting assembly 235 todisengage spring arms 246 c, 247 c from recesses 236 b and 238 c ofmounting assembly 235. It is envisioned that the spring arms/recessescould be incorporated into any articulating surgical device includingstaplers, graspers (See FIG. 3H), powered sealing devices, e.g., RFsealing devices, etc. Further, although two spring arms/recesses areshown, a single spring arm can be provided. Moreover, the articulatingtool assembly need not form part of a DLU but rather can be supporteddirectly on the distal end of a surgical instrument. For example, themounting assembly can be removably or irremovably secured to the toolassembly and secured directly to the distal end of a surgicalinstrument.

Upper housing half 250 and lower housing half 252 are contained withinan outer sleeve 251 of body portion 200 (FIG. 3). Body portion 200includes a cutout 251 a dimensioned to receive a boss or projection 250a formed on upper housing half 250. The positioning of projection 250 awithin cutout 251 a prevents axial and rotational movement of upper andlower housing halves 250 and 252 within outer sleeve 251 of body portion200. In one embodiment, boss 250 a has a substantially rectangularconfiguration having a greater axial dimension than lateral dimension.The greater axial dimension provides increased surface area forpreventing rotation of upper and lower housing halves 250 and 252 withinsleeve 251. A proximal portion 250 b of boss 250 a is ramped. Rampedproximal portion 250 b allows sleeve 251 to be slid over boss 250 a asupper and lower housing halves 250 and 252 are positioned within sleeve251. It is envisioned that boss 250 a may assume other configurations,e.g., circular, square, triangular, etc., and still achieve its intendedfunction. Further, boss 250 a can be repositioned anywhere along upperhousing half 250 or, in the alternative, be positioned on lower housinghalf 252 or partly on each housing half 250 and 252.

The proximal end or insertion tip 193 of upper housing half 250 includesengagement nubs 254 for releasably engaging the distal end of a surgicalinstrument in a bayonet-type fashion (see FIGS. 1A and 7). Housinghalves 250 and 252 define a channel 400 for slidably receiving axialdrive assembly 212 therein. An articulation link 256 is dimensioned tobe slidably positioned within a slot 402 formed between upper and lowerhousing halves 250 and 252. A pair of H-block assemblies 255 arepositioned adjacent the distal end of housing portion 200 and adjacentthe distal end of axial drive assembly 212 to prevent outward bucklingand bulging of drive assembly 212 during articulation and firing ofsurgical stapling apparatus 10. Each H-block assembly 255 includes aflexible body 255 a which includes a proximal end fixedly secured tobody portion 200 and a distal end fixedly secured to mounting assembly235 (FIG. 3).

A retention member 288 is supported on engagement section 270 of axialdrive assembly 212. Retention member 288 includes a pair of fingers 288a which are releasably positioned within slots or recesses 252 a formedin lower housing half 252. In operation, when SULU 16 is attached to asurgical instrument and axial drive assembly 212 is actuated by applyinga predetermined force to an actuation member 516 of the surgicalinstrument 500 (FIG. 11), axial drive assembly 212 is advanced distallyto move drive assembly 212 and retention member 288 distally. Asretention member 288 is advanced distally, fingers 288 a are forced fromrecesses 252 a to provide an audible and tactile indication that thesurgical instrument has been actuated. Retention member 288 is designedto prevent inadvertent partial actuation of DLU 16, such as duringshipping, by maintaining axial drive assembly 212 at a fixed positionwithin DLU 16 until a predetermined axial force has been applied toaxial drive assembly 212.

Axial drive assembly 212 includes an elongated drive beam 266 includinga distal working head 268 and a proximal engagement section 270. In oneembodiment, drive beam 266 is constructed from multiple stacked sheetsof material. Engagement section 270 includes a pair of resilientengagement fingers 270 a and 270 b which mountingly engage a pair ofcorresponding retention slots formed in drive member 272. Drive member272 includes a proximal porthole 274 configured to receive distal end ofa control rod 520 (FIG. 11) of a surgical instrument when the proximalend of DLU 16 is engaged with the body portion 512 of a surgicalinstrument 500.

Referring also to FIGS. 5-10, DLU 16 further includes a lockingmechanism including a locking member 300 and a locking member actuator302. Locking member 300 (FIG. 6) is rotatably supported within alongitudinal or axial slot 310 (FIG. 7) formed in a proximal portion ofupper housing half 250 of body portion 200 of DLU 16. Locking member 300is movable from a first position (FIGS. 7 and 8), in which lockingmember 300 maintains drive assembly 212 in a prefired position, to asecond position (FIGS. 9 and 10), in which drive assembly 212 is free tomove axially.

As illustrated in FIG. 6, locking member 300 includes semi-cylindricalbody 312 which is slidably positioned within transverse slot 310 formedin upper housing half 250 of body portion 200. Body 312 includes aradially inwardly extending cam member 314 and a radially inwardlyextending finger 316. Finger 316 is dimensioned to be slidably receivedwithin a notch or slot 270 c (FIG. 3) formed in drive assembly 212.Engagement of finger 316 in notch 270 c of drive assembly 212 preventsdrive assembly 212 from moving linearly within body portion 200 and,thus, prevents actuation of DLU 16.

Referring to FIGS. 3, 5 and 7, a locking member actuator 302 is slidablypositioned within a axial slot 320 (FIG. 7) formed in upper housing half250 of body portion 200 of DLU 16. Actuator 302 includes a proximalabutment member 322, a distal spring guide 324, and a central cam slot326. Axial slot 320 intersects transverse slot 310 such that cam member314 of locking member 300 is slidably positioned within cam slot 326 oflocking member actuator 302. A biasing member or spring 328 (FIG. 7) ispositioned about spring guide 324 between a distal surface 330 ofactuator 302 and a wall 332 (FIG. 7) defining the distal end of axialslot 320. Spring 328 urges actuator 302 to its retracted position withinaxial slot 320. In its retracted position, abutment member 322 ispositioned on and extends radially outwardly of the proximal end of DLU16 adjacent insertion tip 193 of proximal body portion 200 and cam slot326 is positioned to locate cam member 314 such that finger 316 of lockmember 300 is positioned within notch 270 c of drive assembly 212.

FIGS. 11-15 illustrate DLU 16 and surgical instrument 500 prior to andduring attachment of DLU 16 to surgical instrument 500. Prior toattachment of DLU 16 onto surgical instrument 500, spring 328 urgesactuator 302 to its retracted position to move lock member 300 to itslocked position as discussed above. When insertion tip 193 DLU 16 islinearly inserted into the open end 522 (FIG. 11) of the body portion512 (FIG. 13) of a surgical instrument 500, nubs 254 move linearlythrough slots (not shown) formed in open end 522 of body portion 512. Asnubs 254 pass through the slots, the proximal end 322 a of abutmentmember 322, which is angularly offset from nubs 254, abuts a wall 276 cdefining the slots for receiving nubs 254. As DLU 16 is moved furtherinto body portion 512, locking member actuator 302 is moved from itsretracted position to its advanced position in the direction indicatedby arrow “T” in FIG. 14. As actuator 302 is moved to its advancedposition, lock member 300 is cammed in the direction indicated by arrow“U” in FIG. 14 from its locked position (FIG. 8) engaged with driveassembly 212 to its unlocked position (FIG. 10) to move finger 316 fromnotch 270 c. The locking mechanism including locking member 300 andlocking member actuator 302 prevents accidental or inadvertentadvancement or manipulation of the drive member of DLU 16 such as duringloading of DLU 16 onto a surgical instrument 500.

When DLU 16 has been moved linearly in relation to instrument 500 to aposition wherein a proximal surface 530 of body portion 200 abuts innersurface 276 c of body portion 512 (FIG. 15), DLU 16 can be rotated inrelation to body portion 512 in a bayonet-type action to position nubs254 within openings 536 of body portion 512 to lock DLU 16 onto bodyportion 512. It is envisioned that other coupling types besides bayonetcouplings may be used to connect DLU 16 to instrument 500, e.g., springdetent or snap-fit couplings, friction fit couplings, interlockingmembers, threaded couplings etc.

In an embodiment of the present disclosure illustrated in FIGS. 16-20, alocking assembly 600 is illustrated for use with surgical instrument 500and disposable loading unit 16 (see FIG. 1, for example). In theillustrated embodiments, locking assembly 600 includes a housing 602, apusher 604, a rod 606, a slide 608, at least one spring 610, a camfinger 612, a pivot plate 614 having slots 616 and a link 618. Lockingassembly 600 generally helps tool assembly 17 (see FIG. 1, for example)maintain its position during firing of surgical instrument 500.

Referring to FIGS. 16 and 17, a portion of locking assembly 600 is atleast partially contained within a housing 602. FIG. 16 illustrateslocking assembly 600 disposed in relation to housing 602, while FIG. 17illustrates locking assembly 600 isolated from housing 602. In theillustrated embodiment of FIG. 17, pusher 604 is shown with rod 606extending distally therefrom. Slide 608 extends distally from rod 606and is in a slidable relationship therewith, thus allowing slide 608 tomove axially with respect to rod 606. Spring 610 or pair of springs (notexplicitly shown in this embodiment) distally biases slide 608 from rod606.

Now referring to FIGS. 18-20, cam finger 612 and pivot plate 614 areillustrated. Cam finger 612 extends distally from slide 608 and pivotplate 614 may be disposed on mounting assembly 235 (see FIG. 3), forexample. It is envisioned that pivot plate 614 may be disposed on orincorporated with a portion of tool assembly 17. A plurality of slots616 (five slots 616 are illustrated) is disposed on pivot plate 614 andare sized to accept at least a portion of cam finger 612 therein. Upondifferent amounts of articulation of tool assembly 17 (including nosubstantial articulation) with respect to body portion 512 (see FIG. 1,for example), cam finger 612 is approximately aligned with an individualslot 616 of pivot plate 614. FIGS. 18 and 19 illustrate cam finger 612substantially aligned with a center slot 616 a (hidden from view in FIG.19) and FIG. 20 illustrates cam finger 612 substantially aligned with aside slot 616 b.

Link 618, illustrated in FIGS. 17 and 19, is in mechanical engagementwith pivot plate 614 and cam finger 612. (In FIG. 18, the link has beenremoved.) Link 618 is illustrated having an opening 620 and a slot 622(FIG. 19). Opening 620 is in a pivotal relationship with a boss 624 onpivot plate 614 and slot 622 is slidably engaged with cam finger 612.This relationship allows for articulation of pivot plate 614 withrespect to body portion 512 and for longitudinal translation of slide608 with respect to pivot plate 614.

In operation, upon at least a partial actuation of movable handle 516(see FIG. 1, for example), pusher 604 is forced distally, e.g., viacontrol rod 520 (see FIG. 11, for example), thus causing distaltranslation of cam finger 612 at least partially into a slot 616 ofpivot plate 614. It is envisioned that actuating movable handle 516 toapproximate cartridge assembly 18 and an anvil assembly 20 (see FIG. 1A,for example) also functions to translate cam finger 612 distally. Insuch an embodiment, when articulating tool assembly 17 is in place andclamped on tissue, further articulation cannot be accomplished (withoutreleasing movable handle 516, for example). Thus, locking assembly 600helps maintain articulating tool assembly 17 in position with respect tobody portion 512, prior to emplacing staples into tissue, for example.

As discussed above, spring 610 distally biases slide 608 from rod 606.This biasing provided by spring 610 helps ensure cam finger 612 is notaccidentally or prematurely dislodged from slot 616 of pivot plate 614,which may result in a significant amount of “play” therebetween.Additionally, the distal bias provided by spring 610 helps eliminatemanufacturing tolerances and/or clearances that are present betweenslide 608 and pivot plate 614. It is also envisioned that at least aportion of cam finger 612 and/or slot 616 may be wedge-shaped to helpreduce any unintended movement therebetween. In such an embodiment, adistal portion of cam finger 612 and slot 616 would be narrower than acorresponding proximal portion.

In an embodiment of the present disclosure illustrated in FIGS. 21 and22, a locking assembly 700 is illustrated for use with surgicalinstrument 500 and disposable loading unit 16 (see FIG. 1, for example).In the illustrated embodiment, locking assembly 700 includes an adapter702, a pusher 704, a pivot 706, a biasing element (e.g., a pair ofsprings 708) and a link 710. Locking assembly 700 generally helpsmaintain tool assembly 17 in a predetermined position.

With reference to FIG. 21, adapter 702 of locking assembly 700 isgenerally housed within body portion 512 (see FIG. 1, for example) ofsurgical instrument 500 or within disposable loading unit 16. In theillustrated embodiment, pusher 704 is located distally of a pair ofsprings 708. Pusher 704 is distally biased via the pair of springs 708towards pivot 706 of articulating tool assembly 17. A distal portion ofpusher 704 includes a pusher mating surface 712 (FIG. 22) which isshaped and dimensioned to mate with a pivot mating surface 714 (FIG. 22)disposed adjacent a proximal portion of pivot 706. Link 710 isillustrated in mechanical cooperation with a portion of pusher 704 andpivotably connected to a portion of pivot 706, thus allowingarticulating tool assembly 17 to move between its first position and itssecond position with respect to body portion 512. More specifically,link 710 includes an opening 711 that fits over a protrusion 707 ofpivot 706, thus allowing pivotal movement therebetween. Further, link710 is slidably engaged with a portion of adapter 702, thus allowinglongitudinal movement therebetween.

Now referring to FIG. 22, pusher mating surface 712 is substantiallyflat along a majority of its length in this embodiment. Correspondingly,pivot mating surface 714 is also flat along a majority of its length inthe illustrated embodiment. Thus, the distal bias of pusher 704 towardspivot 706 (in the direction of arrow A) via the pair of springs 708,helps maintain articulating tool assembly 17 in its first,non-articulated, position, as the biasing force helps articulating toolassembly 17 resist pivoting. While two springs 708 are illustrated, moreor fewer springs 708 may be provided.

To pivot articulating tool 17 from its first, non-articulated position,the distal biasing force from pair of springs 708 must be overcome. Sucha pivoting action, moves pusher 704 proximally (in the direction ofarrow B) against the bias of pair of springs 708. It is also envisionedthat pusher mating surface 714 includes detents (not explicitly shown inthis embodiment) to help stabilize articulating jaw member 17 inselected articulated positions.

With continued reference to FIG. 22, pivot 706 includes a shelf 716thereon. As shown in FIG. 22, shelf 716 overlaps at least a portion ofpusher 704 when pusher mating surface 712 is in contact with pivotmating surface 714. Shelf 716 is situated and configured to help preventtissue from being pinched between pusher 704 and pivot 706 whenarticulating tool assembly 17 is rotated and/or articulated.

In an embodiment of the present disclosure illustrated in FIGS. 23-25, amulti-layered drive beam 750 having a plurality of layers 750 a-750 e isillustrated and may be included in a disposable loading unit 16 (seeFIG. 1, for example). A closure apparatus 760, such as an I-beam, isalso illustrated. Closure apparatus 760 includes a horizontal portion762 that is advanceable into camming surface 42 (or other contactsurface) to approximate tool assembly tool assembly 17, as described indetail above with reference to FIG. 2.

With reference to FIG. 24, multi-layered drive beam 750 having fivelayers 750 a-750 e is illustrated. It is envisioned and within the scopeof the present disclosure that fewer or more layers may be used to formmulti-layered drive beam 750. It is also envisioned that multi-layereddrive beam 750 may replace drive beam 266 in other embodiments of thisdisclosure. Use of multi-layered drive beam 750 may provide increasedstrength and flexibility during use, specifically, for instance, whiletool assembly 17 is in an articulated position.

A plurality of cutouts 770 is illustrated in FIGS. 23-25 which extendthrough each layer of multi-layered drive beam 750. Although the figuresshow between five and ten cutouts per layer of multi-layered drive beam750, the exact number of cutouts 770 may be fewer than five, betweenfive and ten, or greater than ten. Additionally, cutouts 770 of adjacentlayers of drive beam 750 may or not align with each other. The use ofcutouts 770 reduces cross-sectional dimensions of drive beam 750 andallows for bending force adjustment. While rectangular cutouts 770 areillustrated, the use of cutouts 770 having other regular or non-regularshapes is also contemplated.

The attachment of each layer 750 a-750 e of multi-layered drive beam 750and the attachment to closure apparatus 760 are illustrated in FIG. 25.In the illustrated embodiment, an outer layer (750 a or 750 e of FIG.24) is affixed to closure apparatus 760 in two locations (each locationbeing indicated by numeral 780 in FIG. 25), via a pair of spot welds,for example. It is also envisioned that each outer layer 750 a, 750 eincludes an aperture 776 that fits over a boss 778 protruding fromclosure apparatus 760. Each outer layer 750 a, 750 e is also affixed toan adjacent layer (e.g., 750 b or 750 d) in two locations (each locationbeing indicated by numeral 781 in FIG. 25), possibly via a pair of spotwelds. Further, each inner layer (e.g., 750 b, 750 c and 750 d) isattached to an adjacent inner layer (for instance, 750 b is attached to750 c; 750 c is attached to 750 b and 750 d; and 750 d is attached to750 c) in two locations, via spot welds, for example. While spot weldingis disclosed as an attachment method, other methods for attaching eachlayer to each other and the outer layers to the closure apparatus areenvisioned and within the scope of the present disclosure. Theillustrated embodiments show attachments points 780 of inner layersadjacent closure apparatus 760, but it is envisioned and within thescope of the present disclosure that attachment points 780 are disposedin other locations on drive beam 750. Additionally, it is envisionedthat at least one layer of drive beam 750 is made of a metal, such asstainless steel. Portions of drive beam 750 and/or closure apparatus 760may also be made of or at least partially coated with a plasticmaterial, as described below. Further, closure apparatus 790 may includea cutting surface 766 (FIG. 23) thereon for cutting tissue.

In an embodiment of the present disclosure illustrated in FIGS. 26 and27, a closure apparatus 800 and a portion of drive beam 802 are shown.Closure apparatus and/or a contact surface (e.g., camming surface 42) oftool assembly 17 (see FIG. 2, for example) may include a plastic surfaceor plastic coating. In this embodiment, closure apparatus 800 isillustrated having a pair of caps 804 at least partially coveringhorizontal portions 806 of closure apparatus 800. Caps 804 may be madeof plastic in this embodiment. Such plastic surfaces disposed on closureapparatus 800 and/or contact surface of tool assembly 17 generallyreduce the amount of friction therebetween vis-à-vis two metal surfaces.That is, a plastic to metal or a plastic to plastic interaction maycreate less friction than interaction between a pair of metal surfaces.This reduced amount of friction may correspond to a reduced firingforce.

It is envisioned that a portion of closure apparatus 800, such as pairof caps 804, is made of plastic, overmolded with plastic or includes aplastic coating. Additionally, a contact surface of tool assembly 17, orat least a portion thereof, may also be made of plastic, be overmoldedwith plastic or include a plastic coating.

In an embodiment of the disclosure, closure apparatus 800 may include anI-shaped cross section, as illustrated in FIGS. 26 and 27. Additionally,closure apparatus 800 and drive beam 802 may be part of a disposableloading unit 16 and/or part of a surgical instrument 500 that is able toarticulate. Further, drive beam 802 may include a single layer or aplurality of layers (as shown in FIG. 26) and at least a portion ofdrive beam 802 may be made of plastic. Still further, closure apparatus800 may include a cutting surface 808 (FIG. 27) thereon for cuttingtissue.

With continued reference to FIGS. 26 and 27, plastic cap 804 may includea reinforced section 810 which may increase the strength of closureapparatus 800 or may provide a stronger connection between cap 804 andhorizontal portion 806 of closure apparatus 800. It is also envisionedthat cap 804 may be removably attached to closure apparatus 800. In suchan embodiment, cap 804 may be removed and replaced if any substantialwearing or damage occurs.

In an embodiment of the present disclosure illustrated in FIGS. 28 and29, a tool assembly 850 is illustrated. Tool assembly 850 of thisembodiment includes a channel 852, a first attachment member 860, asecond attachment member 870, an anvil assembly 880, a first attachmentrod 890 and a second attachment rod 892. First and second attachmentrods 890, 892 provide a strong connection facilitating the elements oftool assembly 850 to remain together.

Channel 852 includes an opening 854 (two openings are illustrated)adjacent its proximal end and first attachment member 860 includes aboss 862 (two bosses are illustrated) extending therefrom. Channel 852is connectable to first attachment member by placing opening(s) 854 overboss(es) 862, thus providing a pivotal connection therebetween. Althoughnot explicitly illustrated in the present embodiment, channel 852 mayhouse a plurality of surgical fasteners or a staple cartridge.

Anvil assembly 880 includes an anvil cover 882 and an anvil 886. Anvil886 is configured for mechanical engagement with anvil cover 882, e.g.,via a snap-fit connection. An aperture 884 extends at least partiallythrough a portion of anvil cover 882. Aperture 884 is configured to fitover a protrusion 872 disposed on second attachment member 870, therebyproviding a connection between anvil assembly 880 and second attachmentmember 870. Additionally, anvil cover 882 includes at least one opening888 extending at least partially therethrough in an embodiment of thedisclosure. Opening 888 is configured to fit over boss 862 of firstattachment member 860. In such an embodiment, anvil assembly 880 may bepivoted with respect to first attachment member 860 and secondattachment member 870.

First attachment member 860 includes a first opening 864 and a secondopening 866 extending therethrough. Second attachment member 870 alsoincludes a first opening 874 and a second opening 876 extendingtherethrough (FIG. 29). Further, first attachment member 860 and secondattachment member 870 are in mechanical engagement, such that firstopenings 864, 874 substantially align and second openings 866, 876substantially align.

To secure first attachment member 860 with second attachment member 870(and thus channel 852 and anvil assembly 880), first attachment rod 890,or a portion thereof, is inserted through first openings 864 and 874. Tofurther secure the elements of tool assembly 850, second attachment rod892, or a portion thereof, is inserted through second openings 866 and876. It is envisioned that first attachment rod 890 and/or secondattachment rod 892 are rivets, such as two-part rivets that aretightenable.

In an embodiment of the disclosure, tool assembly 850 is part of adisposable loading unit, which may be able to articulate. Articulationof tool assembly 850 may be facilitated by pivotably attaching toolassembly 850 to a body portion of a surgical instrument via protrusion874 extending from second attachment member 870 and a link (such as link710 in FIG. 21). Additionally, a method of assembling tool assembly 850,as described above, is contemplated by the present disclosure.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, the above-described lockassembly may be incorporated into a variety of surgical instrumentswhich include DLUs and is not limited to use on linear staplers.Further, the DLU may be configured to receive an insertion tip ofsurgical instrument in contrast to that disclosed. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of various embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. A disposable loading unit, comprising: a drive beam having a proximalengagement portion disposed adjacent a proximal end thereof, the drivebeam defining a first longitudinal axis; a tool assembly including ananvil defining a first contact surface, and a cartridge assemblydefining a second contact surface, wherein the first and second contactsurfaces are at least partially formed from metal, the tool assemblybeing disposed distally of the drive beam and defining a secondlongitudinal axis; and a closure apparatus being formed from metaldisposed adjacent a distal end of the drive beam, the closure apparatusincluding a first portion configured and dimensioned to engage the firstcontact surface of the tool assembly, and a second portion configuredand dimensioned to engage the second contact surface of the toolassembly, whereby distal movement of the drive beam moves the closureapparatus distally into engagement with the first and second contactsurfaces to approximate the anvil and the cartridge assembly, whereinthe first and second portions of the closure apparatus each include aplastic overmold to minimize friction between the first and secondportions of the closure apparatus and the first and second contactsurfaces of the tool assembly.
 2. The disposable loading unit of claim1, wherein the closure apparatus includes at least one plastic cap atleast partially covering a portion thereof.
 3. The disposable loadingunit of claim 2, wherein the plastic cap covers at least one horizontalsurface of the closure apparatus.
 4. The disposable loading unit ofclaim 1, wherein at least a portion of the closure apparatus is made ofplastic.
 5. The disposable loading unit of claim 1, wherein at least aportion of the closure apparatus is overmolded with plastic.
 6. Thesurgical instrument of claim 1, wherein the closure apparatus includesan, I-shaped cross section.
 7. The disposable loading unit of claim 1,wherein at least a portion of the contact surface and at least a portionof the closure apparatus include a plastic surface thereon.
 8. Thedisposable loading unit of claim 1, wherein the drive beam includes aplurality of layers.
 9. The disposable loading unit of claim 1, whereinthe tool assembly being movable from a first position in which thesecond longitudinal axis is substantially aligned with the firstlongitudinal axis to a second position in which the second longitudinalaxis is disposed at an angle to the first longitudinal axis.
 10. Adisposable loading unit, comprising: a drive beam; a tool assemblydisposed distally of the drive beam, the tool assembly including ananvil and a cartridge assembly which are pivotally connected formovement between open and closed positions, the anvil defining a firstcontact surface and the cartridge assembly defining a second contactsurface, the first and second contact surfaces being formed from metal;and a closure apparatus disposed adjacent a distal end of the drivebeam, the closure apparatus including an upper portion configured anddimensioned to engage the anvil and a lower portion configured anddimensioned to engage the cartridge assembly such that distal movementof the closure apparatus moves the anvil and the cartridge assembly fromthe open position to the closed position, the closure apparatus furtherincluding a first plastic surface positioned between the upper portionand the anvil to reduce friction therebetween during distal movement ofthe closure apparatus, and a second plastic surface positioned betweenthe lower portion and the cartridge assembly to reduce frictiontherebetween during distal movement of the closure apparatus to therebyfacilitate a reduction in firing force.
 11. The disposable loading unitof claim 10, wherein the upper and lower portions of the closureapparatus are connected by an intermediate portion positionedtherebetween, the upper and lower portions extending outwardly of theintermediate portion such that the upper portion defines an upperhorizontal portion and the lower portion defines a lower horizontalportion.
 12. The disposable loading unit of claim 11, wherein the firstplastic surface covers the upper horizontal portion and the secondplastic surface covers the lower horizontal portion.
 13. The disposableloading unit of claim 11, wherein the first plastic surface includes afirst reinforced section configured and dimensioned for engagement withthe intermediate portion of the closure apparatus, and the secondplastic surface includes a second reinforced section configured anddimensioned for engagement with the intermediate portion of the closureapparatus, whereby the first and second reinforced sections minimizerelative movement between the first plastic surface and the upperportion of the closure apparatus, and minimize relative movement betweenthe second plastic surface and the lower portion of the closureapparatus.
 14. The disposable loading unit of claim 11, wherein theintermediate portion includes a cutting surface.
 15. The disposableloading unit of claim 10, wherein the first plastic surface is removablyconnected to the upper portion of the closure apparatus, and the secondplastic surface is removably connected to the lower portion of theclosure apparatus.